Hydrovisbreaking process for hydrocarbon containing feed streams

ABSTRACT

At least one decomposable molybdenum compound selected from the group consisting of molybdenum dithiophosphates and molybdenum dithiocarbamates is mixed with a hydrocarbon-containing feed stream. The hydrocarbon-containing feed stream containing such decomposable molybdenum compound is then contacted in a hydrovisbreaking process with hydrogen under suitable hydrovisbreaking conditions.

This invention relates to a hydrovisbreaking process forhydrocarbon-containing feed streams, which substantially minimizescarbon formation. In one aspect, this invention relates to a process forremoving metals from a hydrocarbon-containing feed stream. In anotheraspect, this invention relates to a process for removing sulfur ornitrogen from a hydrocarbon-containing feed stream. In still anotheraspect, this invention relates to a process for removing potentiallycokeable components from a hydrocarbon-containing feed stream. In stillanother aspect, this invention relates to a process for reducing theamount of heavies in a hydrocarbon-containing feed stream.

It is well known that crude oil as well as products from extractionand/or liquefaction of coal and lignite, products from tar sands,products from shale oil and similar products may contain componentswhich make process difficult. As an example, when thesehydrocarbon-containing feed streams contain metals such as vanadium,nickel and iron, such metals tend to concentrate in the heavierfractions such as the topped crude and residuum when thesehydrocarbon-containing feed streams are fractionated. The presence ofthe metals make further processing of these heavier fractions difficultsince the metals generally act as poisons for catalysts employed inprocesses such as catalytic cracking, hydrogenation orhydrodesulfurization.

The presence of other components such as sulfur and nitrogen is alsoconsidered detrimental to the processability of a hydrocarbon-containingfeed stream. Also, hydrocarbon-containing feed streams may containcomponents (referred to as Ramsbottom carbon residue) which are easilyconverted to coke in processes such as catalytic cracking, hydrogenationor hydrodesulfurization. It is thus desirable to remove components suchas sulfur and nitrogen and components which have a tendency to producecoke.

It is also desirable to reduce the amount of heavies in the heavierfractions such as the topped crude and residuum. As used herein the termheavies refers to the fraction having a boiling range higher than about1000° F. This reduction results in the production of lighter componentswhich are of higher value and which are more easily processed.

Hydrofining is a broad term used to describe a process to removecomponents such as metals, sulfur, nitrogen and Ramsbottom carbonresidue from a hydrocarbon containing feed stream and to reduce theamount of heavies in the hydrocarbon containing feed stream.Hydrovisbreaking is a type of hydrofining and is generally characterizedby a heat soak in the presence of hydrogen. Other hydrofining processesmay contact the hydrocarbon containing feed stream with a fixed catalystbed.

A number of different hydrovisbreaking processes are known. Some ofthese processes employ decomposable molybdenum compounds such asmolybdenum hexacarbonyl, molybdenum naphthenate and molybdenum octoate.The decomposable molybdenum compound is mixed with the hydrocarboncontaining feed stream and the hydrocarbon containing feed stream, whichalso contains molybdenum, is heated in the presence of hydrogen undersuitable hydrovisbreaking conditions.

A major problem with prior hydrovisbreaking processes and particularlythose which employ decomposable molybdenum compounds has been theformation of coke, which is extremely undesirable because of the loss ofvaluable hydrocarbon products. It is thus an object of this invention toprovide a hydrovisbreaking process in which the production of coke isreduced with respect to previous hydrovisbreaking processes whichemployed the decomposable molybdenum compounds referred to above.

In accordance with the present invention, at least one decomposablemolybdenum compound selected from the group consisting of molybdenumdithiophosphates and molybdenum dithiocarbamates is mixed with ahydrocarbon-containing feed stream in a hydrovisbreaking process. Thehydrocarbon-containing feed stream, which also contains molybdenum, isheated in the presence of hydrogen under suitable hydrovisbreakingconditions. After being processed in such a manner, thehydrocarbon-containing feed stream will contain a significantly reducedconcentration of metals, sulfur, nitrogen and Ramsbottom carbon residueas well as a reduced amount of heavy hydrocarbon components and onlyrelatively small amounts of dispersed coke particles. Removal of thesecomponents from the hydrocarbon-containing feed stream in this mannerprovides an improved processability of the hydrocarbon-containing feedstream in processes such as catalytic cracking, hydrogenation or furtherhydrodesulfurization. Use of a molybdenum compound selected from thegroup consisting of molybdenum dithiophosphates and molybdenumdithiocarbamates results in improved suppression of coke formation withrespect to the use of molybdenum compounds such as molybdenumhexacarbonyl, molybdenum naphthenate and molybdenum octoate.

Other objects and advantages of the invention will be apparent from theforegoing brief description of the invention and the appended claims aswell as the detailed description of the invention which follows.

Any suitable hydrocarbon-containing feed stream may be processed usingthe above described catalyst composition in accordance with the presentinvention. Suitable hydrocarbon-containing feed streams includepetroleum products, coal pyrolyzates, products from extraction and/orliquefaction of coal and lignite, products from tar sands, products fromshale oil and similar products. Suitable hydrocarbon feed streamsinclude full range (untopped) crudes, gas oil having a boiling rangefrom about 205° C. to about 538° C., topped crude having a boiling rangein excess of about 343° C. and resdiuum. However, the present inventionis particularly directed to heavy feed streams such as heavy full rangecrudes, heavy topped crudes and residuum and other materials which aregenerally regarded as too heavy to be distilled. These materials willgenerally contain the highest concentrations of metals, sulfur, nitrogenand Ramsbottom carbon residues.

It is believed that the concentration of any metal in thehydrocarbon-containing feed stream can be reduced in accordance with thepresent invention. However, the present invention is particularlyapplicable to the removal of vanadium, nickel and iron.

The sulfur which can be removed in accordance with the present inventionwill generally be contained in organic sulfur compounds. Examples ofsuch organic sulfur compounds include sulfides, disulfides, mercaptans,thiophenes, benzylthiophenes, dibenzylthiophenes, and the like.

The nitrogen which can be removed in accordance with the presentinvention will also generally be contained in organic nitrogencompounds. Examples of such organic nitrogen compounds include amines,diamines, pyridines, quinolines, porphyrins, benzoquinolines and thelike.

Any suitable molybdenum dithiophosphate compound may be used in thehydrovisbreaking process. Generic formulas of suitable molybdenumdithiophosphates are: ##STR1## wherein n=3,4,5,6; R¹ and R² are eitherindependently selected from H, alkyl groups having 1-20 carbon atoms,cycloalkyl or alkylcycloalkyl groups having 3-22 carbon atoms and aryl,alkylaryl or cycloalkylaryl groups having 6-25 carbon atoms; ##STR2##wherein p=0,1,2; q=0,1,2; (p+q)=1,2;

r=1,2,3,4 for (p+q)=1 and

r=1,2 for (p+q)=2; ##STR3## wherein t=0,1,2,3,4; u=0,1,2,3,4;

(t+u)=1,2,3,4

v=4,6,8,10 for (t+u)=1; v=2,4,6,8 for (t+u)=2;

v=2,4,6 for (t+u)=3; v=2,4 for (t+u)=4.

Sulfurized oxomolybdenum (V) O,O'-di(2-ethylhexyl)phosphorodithioate ofthe formula Mo₂ S₂ O₂ [S₂ P(OC₈ H₁₇)₂ ] is particularly preferredadditive.

Any suitable molybdenum dithiocarbamate compound may be used in thehydrovisbreaking process. Generic formulas of suitable molybdenum (III),(IV), (V) and (VI) dithiocarbamates are: ##STR4## wherein n=3,4,5,6;m=1,2; R¹ and R² are either independently selected from H, alkyl groupshaving 1-20 carbon atoms, cycloalkyl groups having 3-22 carbon atoms andaryl groups having 6-25 carbon atoms; or R¹ and R² are combined in onealkylene group of the structure ##STR5## with R³ and R⁴ beingindependently selected from H, alkyl, cycloalkyl and aryl groups asdefined above, and x ranging from 1 to 10. ##STR6## wherein p=0,1,2;q=0,1,2; (p+q)=1,2;

r=1,2,3,4 for (p+q)=1 and

r=1,2 for (p+q)=2; ##STR7## wherein t=0,1,2,3,4; u=0,1,2,3,4;

(t+u)=1,2,3,4

v=4,6,8,10 for (t+u)=1; v=2,4,6,8 for (t+u)=2;

v=2,4,6 for (t+u)=3, v=2,4 for (t+u)=4.

Molybdenum(V) di(tridecyl)dithiocarbamate is a particularly preferredadditive.

Any suitable concentration of the molybdenum additive may be added tothe hydrocarbon-containing feed stream. In general, a sufficientquantity of the additive will be added to the hydrocarbon-containingfeed stream to result in a concentration of molybdenum metal in therange of about 1 to about 1000 ppm and more preferably in the range ofabout 3 to about 300 ppm.

It is noted that one of the particular advantages of the presentinvention is the very small concentrations of molybdenum which may beused. This substantially improves the economic viability of the process.

The hydrovisbreaking process can be carried out by means of any suitableapparatus whereby there is achieved a contact of the hydrocarboncontaining feed stream, the decomposable molybdenum compound andhydrogen under suitable hydrovisbreaking conditions. Thehydrovisbreaking process can be carried out as a continuous process oras a batch process. The hydrovisbreaking process is in no way limited tothe use of any particular type of process or apparatus.

The molybdenum compound may be combined with the hydrocarbon-containingfeed stream in any suitable manner. The molybdenum compound may be mixedwith the hydrocarbon-containing feed stream or a solid or liquid or maybe dissolved in a suitable solvent (preferably an oil) prior tointroduction into the hydrocarbon-containing feed stream. Any suitablemixing time may be used. However, it is believed that simply injectingthe molybdenum compound into the hydrocarbon-containing feed stream issufficient. No special mixing equipment or mixing period are required.

In a continuous process, the molybdenum compound is mixed with thehydrocarbon containing feed stream prior to introducing the hydrocarboncontaining feedstream into the reactor. For a batch process, it is alsogenerally more convenient to add the molybdenum compound to thehydrocarbon-containing feed stream before the hydrocarbon containingfeed stream is introduced into the reactor and the reactor ispressurized with hydrogen gas. However, if desired, the molybdenumcompound may be added to the hydrocarbon containing feed stream afterthe hydrocarbon containing feed stream is introduced into the batchreactor but before the hydrovisbreaking process is begun.

The pressure and temperature at which the molybdenum compound isintroduced into the hydrocarbon-containing feed stream is not thought tobe critical. However, a temperature above 100° C. is recommended.

Many hydrofining processes and some hydrovisbreaking processes arecarried out using catalyst compositions. Such catalyst compositionsgenerally comprise a support such as alumina, silica or silica/alumina.Catalyst compositions may also contain a promoter with typical promotersbeing the metals group VIB, group VIIB, and group VIII of the PeriodicTable. The hydrovisbreaking process of the present invention isdistinguished from hydrofining or hydrovisbreaking processes whichemploy such catalyst composition in that such catalyst compositions arenot employed in the hydrovisbreaking process of the present invention.

Any suitable reaction time in the hydrovisbreaking process may beutilized. In general, the reaction time will range from about 0.01 hoursto about 10 hours. Preferably, the reaction time will range from about0.1 to about 5 hours and more preferably from about 0.25 to about 3hours. Thus, for a continuous process, the flow rate of the hydrocarboncontaining feed stream should be such that the time required for thepassage of the mixture through the reactor (residence time) willpreferably be in the range of about 0.1 to about 5 hours and morepreferably about 0.25 to about 3 hours. For a batch process, thehydrocarbon containing feed stream will preferably remain in the reactorfor a time in the range of about 0.1 hours to about 5 hours and morepreferably from about 0.25 hours to about 3 hours.

The hydrovisbreaking process can be carried out at any suitabletemperature. The temperature will generally be in the range of about250° C. to about 550° C. and will preferably be in the range of about380° to about 480° C. Higher temperatures do improve the removal ofmetals but temperatures should not be utilized which will have adverseeffects on the hydrocarbon-containing feed stream, such as increasedcoking, and also economic considerations must be taken into account.Lower temperatures can generally be used for lighter feeds.

Any suitable hydrogen pressure may be utilized in the hydrovisbreakingprocess. The reaction pressure will generally be in the range of aboutatmospheric to about 10,000 psig. Preferably, the pressure will be inthe range of about 500 to about 3,000 psig. Higher hydrogen pressurestend to reduce coke formation but operation at high pressure may haveadverse economic consequences.

Any suitable quantity of hydrogen can be added to the hydrovisbreakingprocess. The quantity of hydrogen used to contact thehydrocarbon-containing feed stock, either in a continuous or batchprocess, will generally be in the range of about 100 to about 20,000standard cubic feet per barrel of the hydrocarbon-containing feed streamand will more preferably be in the range of about 500 to about 5,000standard cubic feet per barrel of the hydrocarbon-containing feedstream.

The following examples are presented in further illustration of theinvention.

EXAMPLE I

In this example the experimental setup for batch-type hydrovisbreakingof heavy oils is described. About 100 grams of a topped (950° F.+) Hondoheavy crude (containing 18.2 weight-% Ramsbottom C, 6.2 weight-% S, 730ppm (V+Ni), 0.55 weight-% xylene insolubles and a 1000° F.+fraction of85.1 weight-%) plus appropriate amounts of a decomposable molybdenumcompound were added to a 300 cc stirred autoclave (Autoclave Engineers,Inc., Erie, Pa.), which was preheated to about 250° F. The unit wassealed, alternatively pressured with H₂ and vented so as to eliminateair, and finally pressured with H₂ to the desired starting pressure(about 1400 psig). Stirring at about 1000 r.p.m. and rapid heating up tothe test temperature about 800° F. was carried out. During the test run,hydrogen gas was added so as to maintain a constant pressure of about2000-2300 psig at the final test temperature.

After heating at about 800° F. for about 60 minutes, the unit was cooledas quickly as possible, depressurized and opened. The liquid product wascollected and analyzed. Primarily, the amount of dispersed cokeparticles was determined (by filtration through a 0.45 μm membranefilter and weighing). Other test parameters were Ramsbottom carbon (ASTMD524), density of 60° F., xylene insoluble content and the amount of the1000° F.+ fraction of the liquid product.

EXAMPLE II

This example illustrates the results of hydrovisbreaking tests inaccordance with the procedure outlined in Example I. The followingdecomposable molybdenum compounds were tested:

A: Molyvan® 807, a mixture of about 50 weight-% molybdenum (V)ditridecyldithiocarbamate and about 50 weight-% of an aromatic oil(specific gravity: 0.963; viscosity at 210° F.: 38.4 SUS); Molyvan® 807contains about 4.6 weight-% Mo; it is marketed as an antioxidant andantiwear additive by R. T. Vanderbilt Company, Norwalk, Conn.;

B: Molyvan® L, a mixture of about 80 weight-% of a sulfided molybdenum(V) dithiophosphate of the formula Mo₂ S₂ O₂ [PS₂ (OR)₂ ] wherein R isthe 2-ethylhexyl group, and about 20 weight-% of an aromatic oil (seeabove); marketed by R. T. Vanderbilt Company;

C: Mo(CO)₆, marketed by Aldrich Chemical Company, Milwaukee, Wis.;

D: Molybdenum (V) naphthenate, Mo(C₁₀ H₂ CO₂)₅ ; marketed by ShepherdChemical Company, Cincinnati, Ohio.

E. Molybdenum (IV) octoate, MoO(C₇ H₁₅ CO₂)₂ ; containing about 8weight-% Mo; marketed by Shepherd Chemical Company.

Results are summarized in Table I.

                                      TABLE I                                     __________________________________________________________________________                        1     2     3    4    5                                   Run No              (Invention)                                                                         (Invention)                                                                         (Control)                                                                          (Control)                                                                          (Control)                           __________________________________________________________________________    Mo Additive         A     B     C    D    E                                   Mo Concentration (ppm) in Feed                                                                    50    50    50   50   50                                  Formed Coke (Wt-% of Liquid Product)                                                              3.2   4.1   8.9  8.4  7.8                                 Conversion of 1000° F.+ Fraction (%)                                                       67.0  65.5  68.9 70.7 73.1                                Ramsbottom C (Wt-% of Liquid Product)                                                             10.2  9.9   10.1 10.7 10.1                                Xylene Insol. (Wt-% of Liquid Product)                                                            0.5   0.4   0    0.3  0.2                                 Density of Liquid Product (60° F.; g/cc)                                                   0.930 0.931 0.926                                                                              0.925                                                                              0.919                               API Gravity of Liquid Product (60° F.)                                                     20.4  20.3  21.1 21.3 22.3                                __________________________________________________________________________

Data in Table I show that, unexpectedly, molybdenum dithiocarbamate(compound A) and molybdenum dithiophosphate (compound B) causedsignificantly lower coke formation than three other molybdenum compoundsduring the hydrovisbreaking of the 950° F.+ topped crude at about 800°F./2000-2300 psig H₂ during a period of about 60 minutes. Ramsbottomcarbon and xylene insoluble contents in the liquid product werecomparable for all runs. The API gravity of the product was slightlylower in the invention runs and so was the 1000F.+ conversion.

EXAMPLE III

In this example the experimental setup for the continuoushydrovisbreaking of heavy oils is described. A topped (650° F.+) Hondoheavy crude (containing 12.1 weight-% Ramsbottom C, 5.6 weight-% S, 480ppm (Ni+V), a 1000° F.+ fraction of 62.0 weight-%, and having an APIgravity of 90.0) plus, when desired, molybdenum compounds were stirredin a heated feed vessel. The oil feed was pumped at a rate of about 2liters per hour into a stainless steel pipe of about 1/4" inner diameterand was mixed with hydrogen gas (pressure: 1800 psig). The oil-gasmixture was heated to a temperature of almost 820° F. in a 60 feet longcoiled stainless steel tube surrounded by an electric furnace andcharged through an induction tube extending close to the bottom of aheated reactor (4 inch diameter and 26 inch length) where it mixed withthe reactor contents. The product exited through an eduction tube, whichwas positioned so as to provide a liquid volume of about 1 liter andthus an average residence time of the oil-gas mixture of about 30minutes at the reaction temperature of about 820° F.

The product passed through a pressure let-down valve into a series ofphase separators and coolers. All liquid fractions were combined, andwere analyzed as described in Example I. A tracer was introduced in thegaseous product stream. The tracer was analyzed in a gas chromatographso as to calculate gas flows and hydrogen consumption. Results aresummarized in Table II.

                                      TABLE II                                    __________________________________________________________________________                        6     7     8    9    10                                  Run No              (Invention)                                                                         (Invention)                                                                         (Control)                                                                          (Control)                                                                          (Control)                           __________________________________________________________________________    Mo Additive         A     B     C    D    E                                   Mo Concentration (ppm) in Feed                                                                    80    80    80   80   80                                  Formed Coke (Wt-% of Liquid Product)                                                              3.1   3.5   6.6  7.7  7.5                                 Conversion of 1000° F.+ Fraction (%)                                                       53.4  54.6  60.4 59.1 59.9                                Gas Formation (SCF/bbl. of Oil Feed)                                                              265   254   292  304  312                                 H.sub.2 Consumption (SCF/bbl. of Oil Feed)                                                        455   430   246  300  262                                 __________________________________________________________________________

Data in Table II confirm the results of Table I: lower coke formationwhen molybdenum dithiocarbamate and dithiophosphate (compounds A and B,Runs 6 and 7) were employed. Hydrogen consumption was significantlyhigher in Runs 6 and 7, whereas 1000° F.+ conversion and gas formationwere somewhat lower in these runs than in control runs (Runs 8, 9 and10).

Reasonable variations and modifications are possible within the scope ofthe disclosure and the appended claims to the invention.

That which is claimed is:
 1. A process for hydrovisbreaking ahydrocarbon-containing feed stream consisting essentially of the stepsof:introducing a suitable decomposable molybdenum dithiophosphatecompound into said hydrocarbon-containing feed stream; and contactingsaid hydrocarbon-containing feed stream containing said decomposablemolybdenum dithiophosphate compound under hydrovisbreaking conditionswith hydrogen.
 2. A process in accordance with claim 1 wherein saiddecomposable molybdenum dithiophosphate compound is selected from thegroup having the following generic formulas: ##STR8## wherein n=3,4,5,6;R¹ and R² are either independently selected from H, alkyl groups having1-20 carbon atoms, cycloalkyl or alkylcycloalkyl groups having 3-22carbon atoms and aryl, alkylaryl or cycloalkylaryl groups having 6-25carbon atoms; ##STR9## wherein p=0,1,2; q=0,1,2; (p+q)=1,2;r=1,2,3,4 for(p+q)=1 and r=1,2 for (p+q)+2; ##STR10## wherein t=0,1,2,3,4;u=0,1,2,3,4; (t+u)=1,2,3,4 v+4,6,8,10 for (t+u)=1; v=2,4,6,8 for(t+u)=2; v+2,4,6 for (t+u)=3, v=2,4 for (t+u)=4.
 3. A process inaccordance with claim 2 wherein said decomposable molybdenumdithiophosphate compound is oxymolybdenum (V)O,O'-di(2-ethylhexyl)phosphorodithioate.
 4. A process in accordance withclaim 1 wherein a sufficient quantity of said decomposable molybdenumdithiophosphate compound is added to said hydrocarbon-containing feedstream to result in a concentration of molybdenum in saidhydrocarbon-containing feed stream in the range of about 1 to about 1000ppm.
 5. A process in accordance with claim 1 wherein a sufficientquantity of said decomposable molybdenum dithiophosphate compound isadded to said hydrocarbon-containing feed stream to result in aconcentration of molybdenum in said hydrocarbon-containing feed streamin the range of about 3 to about 300 ppm.
 6. A process in accordancewith claim 1 wherein said hydrovisbreaking conditions comprise areaction time in the range of about 0.01 hour to about 10 hours, atemperature in the range of about 250° C. to about 550° C., a pressurein the range of about atmospheric to about 10,000 psig, and a hydrogenaddition in the range of about 100 to about 20,000 standard cubic feetper barrel of said hydrocarbon-containing feed stream.
 7. A process inaccordance with claim 1 wherein said hydrovisbreaking conditionscomprise a reaction time in the range of about 0.1 hours to about 5hours, a temperature in the range of about 380° C. to about 480° C., apressure in the range of about 500 to about 3,000 psig, and a hydrogenaddition in the range of about 500 to about 5,000 standard cubic feetper barrel of said hydrocarbon-containing feed stream.
 8. A process inaccordance with claim 1 wherein said hydrovisbreaking conditionscomprise a reaction time in the range of about 0.25 hours to about 3hours, a temperature in the range of about 380° C. to about 480° C., apressure in the range of about 500 to about 3,000 psig, and a hydrogenaddition in the range of about 500 to about 5,000 standard cubic feetper barrel of said hydrocarbon-containing feed steam.
 9. A process inaccordance with claim 1 wherein said hydrocarbon-containing feed streamis a petroleum residuum.